To develop and test telecommunications equipment, a myriad of transmitting equipment products have been utilized to generate and apply to the telecommunications equipment varying errored digital signal patterns. These various equipment products, while functional, do not have the flexibility or control to adequately generate the errored patterns necessary to thoroughly test the performance of telecommunications equipment. For example, the HP 3781, HP 3780, and HP 3782 pattern generators available from Hewlett-Packard offer high bit rates, but only provide SF superframing formats. Their error generation capabilities are limited to producing a single error occurrence over which the user has no timing control, and only a limited selection of error rates are possible. The Phoenix 5575A-T1 Micro BERT available from Phoenix offers framed format generation of various framing formats and line codes. Its error generation capabilities allow single error occurrence or error rate generation of line code and framing bits, however, it does not control which bits are errored. The T-Bird 211 T-Carrier Analyzer, available from T-Bird, can generate any number of consecutive frame bit errors, however, the generation of the errors is limited to the pressing of a switch which generates the errored frame, limiting the switching ability of generating a good frame and then an errored framed when desired. The Tekelec TEB-ZOA-DS1 Frame Simulator and Analyzer, available from Tekelec, provides various generating and erroring capabilities, but will not provide ZBTS1 line coding or the generation of Facility Data Link messages and lacks the control necessary to quickly switch between errored and unerrored generated patterns. In addition, errors can only be inserted into unerrored framed patterns, as opposed to inserting errors into an already errored pattern.
The various pattern generator products utilize hardware customized or specific to the assembly of the user specified channel content, framing, signal bits, etc. Therefore, when changes are made in the specifications of the framing patterns, data link formats, and the like, the products require hardware modifications to meet the new requirements. Thus, there is a need for a universal error pattern generator which provides flexible and detailed pattern control to test the performance of telecommunications equipment, and which could replace the myriad of pattern generator products now available.